Problem running my first program

Question

Florian Spicher 2021-10-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1565536-problem-running-my-first-program

回答： Walter Roberson 2021-10-17

I'm trying to use the function fsolve to find the solution of my system of equations.

First, I defined my function NL_Syst_HW4 (see below), which is my system. My problem is when I run fsolve(NL_Syst_HW4, [0,0,0]) it tells me I don't have enough imput argument. Still, my function seems to work since it returns me value when I implement it with (say) [0,0,0].

Thanks for the help!

function [F]=NL_Syst_HW4(x)
     
     F1=92*x(1)+75*x(2)+20*x(3)-60*exp(1);
     F2=15*x(1)+16*x(2)+6*x(3)-12*exp(1);
     F3=2*x(1)+3*x(2)+6*x(3)+3*(2-2*exp(1));
     
     F=[F1,F2,F3];
end

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2021-10-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1565536-problem-running-my-first-program#answer_810206

在 MATLAB Online 中打开

fsolve(@NL_Syst_HW4, [0,0,0])

Remember that matlab processes arguments before making the calls. The argument NL_Syst_HW4 has to be processed, and at that point, matlab has no idea that a function handle is expected there. MATLAB does not look and see "oh, fsolve expects a function handle so treat NL_SYST_HW4 as a function handle": matlab processes NL_Syst_HW4 first and passes the result to fsolve.

But what is the result of processing NL_SYST_HW4? Well, that is not a variable so matlab checks to see if it is a function. Having found it to be a function, matlab calls the function with all the provided parameters.. which is no parameters at all. And then the function complained because you did not pass enough parameters.